one round that won't chamber...

My guess is that the 25 rounders look more like a 30 round AR15 mag(same length). The 32 round ProMags do not.

Well, you aren't the first or the last to pull a DUH. Join the club.

Sure it will ... press the bolt release!

There is no standard for .22 except that the 10/22 has used a 25 round large mag for awhile. As a result many rimfire competitions specify max 25 in the rifle mags. Its just a generally accepted size.

Magpul does not make or sell magazines for .22 rifles. Wishing it won't make it happen.

Before going to the range on Sunday; I did a comparision of the 25 & 32 round mags. The tab that locks the bolt back after the last round is a little longer on the 32 round mag. With only placing 2 rounds in each mag and cycling the charging handle; the 32 rnd mag would lock the bolt back with 1 round still in it. Took it to the range and fired 250 rounds. There were not any stragglers left in the mag; emptied each one everytime.

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GO HOGS

On the 10rd mags that I modified to 32rd, the tab needed to be cut down slightly as it would lock back every time with 1 round left in the mag, both with live fire and by hand-cycling the gun. Cutting it down gradually very little at a time to where it would only lock back on empty mag worked out, but I haven't measured yet what that magic number is......waiting to compare to S&W OEM 25rd mag before declaring a measurement "good to go".

Which "tab" are you refering to? The 2 10's I just converted both lock back with 1 round left. Is it the tab on the follower that protrudes through the back of the magazine?

I shot 2 mags yesterday that I modified by cutting the base of the follower down to 1/2" (same as factory 32 rounder). I shot 4 full cycles through 2 different mags and had only one failure to feed in the bunch. Emptied every mag to empty and held the bolt open every time.

Yes, that's what engages the bolt latch.

So, in theory, shaving that down a bit should remedy the issue? I can see where it is engaging the bolt catch with a single round in the mag, so if it were a little shorter, it should be fine?

That is correct.

Ok, so I took the followers out and filed the tab down on one of them. I took about 1/8" off of the tab that catches the bolt catch, and reassembled the mag. Sure enough, it loads the last round and still catches the bolt when empty. Here's a pic for comparison. The follower on the left is the unaltered promag follower. Middle is the filed down one. The one on the right is the stock S&W follower. You can see how the tab on the S&W follower doesn't come up nearly as high as the ones on the promags. Sorry for the blurry pic. The phone doesn't take great pics indoors. It doesn't take much though. Like I said, I only filed off about an 1/8" and it seems to work perfectly now. Hope this helps.

Diesel, exactly what I was referring to, good picture!

Thanks for the comparison pic! I've yet to take my promags out, but if I do run into the straggler problem I've got one possible solution.

I've had this problem too with the promag.

We've got jackets.

Thanks for the pics Diesel! If I get time this week, I'll try shaving a few and see if I can make it out to the range and do some testing and have a permanent fix!

Thank you guys for the tip. I filed a little off each tab on the 10 round Promags and they hand cycled perfectly.

So the part filed down is the plastic piece in the center correct?

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M&P 2.0 9mm-Shield9-Shield45

Yes it is.

Just wondering if the S&W follower will interchange with the ProMag follower.

I don't know if it's the picture, but the OEM follower looks better made.

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Boz

Better rounds on it, just better refined tooling.

The only way to know is to try it.

I measured the 12 ProMag 10rd mags that I converted to 32rd. From the top of the mag feed tower to how far down I cut the actuation tab on the follower was ~8.5mm. (I did not measure from the top of the follower to the tab, please note that distinction.)

Cut yours just a touch at a time and try it out. Better to cut too little and keep trying it rather than cut too much and lose bolt hold open functionality!

(Also double-check the dimension I listed above, as the setup I'm running is a CMMG dedicated .22 upper with the Better-Mag 15-22 adapter to use the 15-22 mags with CMMG .22 conversion. My 15-22 was unavailable for a short time in order to verify all is good with the ProMags running with the capacity and bolt hold open modifications on the range. I'll have my 15-22 back tonight.)

Last round on my Promag is not a straggler but an FTF. I'd rather have it be a straggler. Trying to troubleshoot this I swap the S&W follower into the Promag and the last round fed in OK. So I thought the Promag follower was faulty and installed it in the S&W magazine. Well the last round fed in OK. Put back the followers in their respective magazines. FTF on the last round on the Promag again. Note that during this testing I only load 2 rounds on each magazine, fire one shot and see how the last round feeds. When I load one round in the Promag magazine, it feeds OK.

One thing I learned is the S&W and Promag followers are swappable, YMMV.

Another thing that I noticed is that the ramp angle on Promag follower is different than the S&W.